Fully Decentralized Modular Approach for Parallel Converter Control Marc Cousineau, Zijian Xiao Université de Toulouse INPT, CNRS, LAPLACE (Laboratoire Plasma et Conversion d'Energie) Toulouse, FRANCE marc.cousineau@laplace.univ-tlse.fr Abstract— A completely decentralized solution (real masterless) for parallel converter control is presented. A control module dedicated to each switching cell, communicating with its neighboring modules, is presented in detail. It is able to provide the computation of the common mode duty cycle, the balancing of the leg currents and the proper phase shift for the interleaved carriers of the converter in a decentralized manner. The implementation of a converter using a large number of parallel legs becomes easy because an identical control module is associated with each switching cell and the modules are connected together in a daisy-chain configuration. This approach eliminates the use of a centralized control circuit. It works regardless of the number of legs and provides the ability to add or remove dynamically a leg easily. A characterisation board has been made and demonstrates the validity of the solution. Moreover it shows that, using this modular control approach, a leg of the converter may be add or remove dynamically without any additional control consideration. I. INTRODUCTION Nowadays, parallel DC-DC interleaved converters are widely used in various power conversion applications such as VRM (Voltage Regulator Module) for instance. They offer the advantage of reducing the magnitude of currents flowing through the filter inductors and the semiconductors. Moreover, the output current ripple is significantly reduced which makes it possible to reduce the value of the output filter capacitor. Furthermore, a low current ripple may be obtained also in each leg by coupling the inductances together. The current constraints are reduced in the legs by increasing the number of parallel legs which allows using fast switches with a low current rating. However, with a high leg number N (N>6 for instance), a large number of connections are required between control circuit (Master) and the switching cells. In such converters, the switching cells have to be controlled by interleaved PWM signals (equal duty-cycles with a relative phase-shift = 2.π/N). Current-sharing control techniques are necessary to distribute power among the parallel legs. At last, a global voltage loop is implemented to compute the common mode duty-cycle. For VRM applications, the output voltage is often provided by an AVP-type regulator (Adaptive Voltage Positioning). It decreases when the output current rises. Voltage Regulation Loop (or AVP) Switches + Drivers Switches + Drivers Switches + Drivers Switches + Drivers I1 IN-1 I2 IN Interleaved Carrier Generator L L L L Balancing Current Computation N PWM Orders N sensors IC dedicated to computations Voltage Feedback N IC dedicated to switching purpose … Iout Load Vout Iout I1 IN-1 I2 IN L L L L Load Vout AVP AVP AVP AVP Voltage Feedback loop Vref Switches + Drivers Switches + Drivers Switches + Drivers Switches + Drivers N identical Control Modules Balancing Balancing Balancing Balancing Carrier Carrier Carrier Carrier Intercell communication Empty Vref (a) (b) Fig. 1. N-leg parallel converter control: a) Standard approach, b) Decentralized method. 978-1-4673-4355-8/13/$31.00 ©2013 IEEE 237